Oxidation dyes

ABSTRACT

1,3-disubstitued nitrobenzenes of the general formula I: ##STR1## in which X is a hydroxyl group or an amino group and R 1  is hydrogen or a C 1-4  alkyl group and their salts are suitable for use as an oxidation dye precursor of the coupler type, together with prior art primary intermediate components, for the production of oxidation dyes, preferably for the production of hair colorants. With developers of the p-phenylenediamine, p-aminophenol, 2.5-diaminopyridine, and 2,4,5,6-tetraaminopyrimidine types, primarily brown hues with great light stability are formed.

FIELD OF THE INVENTION

This invention relates to the use of 1,3-disubstituted 2-nitrobenzenesfor the production of oxidation dyes, more particularly for theproduction of hair dyes.

STATE OF THE INVENTION

Oxidation dyes contain oxidation dye precursors in a suitable carrier.The oxidation dye precursors used are primary intermediate compoundswhich form intensive colors by oxidative coupling with one another orwith one or more color modifiers in the presence of atmospheric oxygen.Suitable primary intermediate compounds are, for example, primaryaromatic amines containing another free or substituted hydroxy or aminogroup in the para position or ortho position and also diaminopyridines,heterocyclic hydrazone derivatives, 4-aminopyrazolone derivatives andtetraaminopyrimidines.

The dyes obtainable by coupling of the primary intermediate componentswith one another are generally unsatisfactory. However, colors of highintensity and brilliance can often be obtained by coupling with phenolsor aromatic amines.

Suitable color modifiers are, for example, m-phenylene diamines,m-aminophenols, resorcinols, naphthols and pyrazolones.

One of the most important applications of oxidation dyes is in thecoloring of hair. Good oxidation hair dye precursors have to satisfyabove all the following requirements: they must produce the requiredtints in sufficient intensity in the oxidative coupling reaction. Inaddition, they must be readily absorbable by human hair withoutexcessively staining the scalp. In addition, the dye should be absorbeduniformly, i.e. the more seriously damaged hair ends should not becolored to a greater extent than the less damaged hair roots. The colorsproduced should show high stability to heat, light and the chemicalsused for permanent waving. Finally, the oxidation hair dye precursorsshould be toxicologically and dermatologically safe.

Although nitrophenols and nitroanilines have certain coloring propertiesfor keratin fibers, they are not normally suitable as color modifiersbecause the nitro group deactivates the aromatic core for the couplingreaction. The use of resorcinol as a color modifier is known from DEPSS162 625 and 276 761. However, the light stability properties ofoxidation hair colors obtainable with resorcinol are only moderate.m-Phenylenediamine and m-tolylenediamine have also long been used ascolor modifiers.

DESCRIPTION OF THE INVENTION

However, these color modifiers do not provide natural brown tones withthe usual primary intermediate components.

SUMMARY OF THE INVENTION

It has now been found that 1,3-disubstituted nitrobenzenes correspondingto general formula I: ##STR2## in which X is a hydroxyl group or anamino group and R¹ is hydrogen or a C₁₋₄ alkyl group, and salts thereofare suitable as color modifiers together with known primary intermediatecompounds for producing intensive oxidation colors.

The oxidation colors obtainable in this way are readily absorbed by hairand other keratin fibers and show high stability to light and heat.

DESCRIPTION OF PREFERRED EMBODIMENTS

Accordingly, the present invention also relates to hair dyes containingoxidation dye precursors in a carrier, 1,3-disubstituted nitrobenzenescorresponding to formula I or salts thereof as color modifiers and oneor more primary intermediate components typically encountered inoxidation dyes being present as the oxidation dye precursors.

The 1,3-disubstituted nitrobenzenes corresponding to general formula Iare compounds known from the literature or may be synthesized by methodsknown from the literature. 2-Nitroresorcinol is described, for example,in J. Org. Chem. 16 (1951), 611 while 2-nitro-m-phenylene diamine isdescribed in J. Chem. Soc. Perkin Trans. I (1988), 1940-1941. They aresuitable as color modifiers for a number of known primary intermediatecompounds and produce intensive colors in the form of brown tones.Suitable primary intermediate components are, for example, aromaticamines or phenols containing one or more other NH₂ groups, NHR groups orNR₂ groups (R=C₁₋₄ alkyl) in the para or ortho position, an optionallysubstituted hydroxyalkyl or aminoalkyl group containing 2 to 4 carbonatoms, o- and p-aminophenol ethers, diaminopyridines, heterocyclichydrazone derivatives such as for example, 1-methyl-2-pyrrolidonehydrazone, aminopyrazolone derivatives, such as4-amino-1-phenyl-3-carbamoyl-5-pyrazolone, 2,4,5,6-tetraaminopyrimidineand N-substituted derivatives thereof and4-hydroxy-2,5,6-tetraaminopyrimidines. Examples of particularly suitableprimary intermediate components are given in the following as componentsD1-D10.

In the hair dyes according to the invention, the compounds correspondingto formula I may be used either in free form or also in the form of asalt. 2-Nitroresorcinols form salts with bases. Suitable salts are, forexample, the alkali metal, ammonium, mono-, di- and tri-alkanolammoniumsalts containing 2 to 4 carbon atoms in the alkanol group or even themagnesium or calcium salt. 2-Nitro-m-phenylenediamines form salts withacids. Suitable salts are, for example, the hydrochlorides, sulfates,phosphates, acetates, propionates, lactates or citrates.

In addition to the 1,3-disubstituted nitrobenzenes corresponding toformula I, the hair dyes according to the invention may also containother known color modifiers necessary for modifying the tints and forproducing naturallooking tones. Known color modifiers of the type inquestion are, for example, m-phenylenediamines, 2,4-diaminophenolethers, bis-(2,4-diaminophenoxy)-alkanes, o- and m-cresol, resorcinol,hydroquinone, pyrogallol, pyrocatechol, α-naphthol, 1,5- or1,7-dihydroxynaphthalene, 1-phenyl-3-methyl-5-pyrazolone,1-phenyl-3-amino-5-pyrazolone, 1phenyl-3,5-diketopyrazolidine,1-methyl-7-dimethylamino-4-hydroxy-2-quinolone orimidazo[1,2a]pyridin-2(3H)-ones.

The 1,3-disubstituted nitrobenzenes corresponding to formula I and thecolor modifiers additionally used, if any, are generally added to thehair dyes according to the invention in substantially molar quantities,based on the primary intermediate components used. Although it hasproved useful to employ molar quantities, there is no disadvantage inusing a certain excess of individual oxidation dye precursors so thatprimary intermediate components and color modifiers may be present in amolar ratio of 1:0.5 to 1:2.

The oxidation dye precursors or substantive dyes otherwise present inthe hair dyes do not have to be individual chemical compounds. On thecontrary, they may also be mixtures of the modifier and primaryintermediate components to be used in accordance with the invention.

To produce the hair dyes according to the invention, the oxidation dyeprecursors are incorporated in a suitable cosmetic carrier. Suchcarriers are, for example, creams, emulsions, gels or evensurfactant-containing foaming solutions, for example shampoos or otherpreparations suitable for application to the hair. Typical constituentsof such cosmetic preparations are, for example, wetting agents andemulsifiers, such as anionic, nonionic, ampholytic or zwitterionicsurfactants, for example soaps, fatty alcohol sulfates,alkanesulfonates, α-olefin sulfonates, fatty alcohol polyglycol ethersulfates, ethylene oxide adducts with fatty alcohols, fatty acids andalkylphenols, sorbitan fatty acid esters and fatty acid partialglycerides, fatty acid alkanolamides and also thickeners such as, forexample, methyl or hydroxyethyl cellulose, starch, fatty components suchas, for example, fatty alcohols, paraffin oils or fatty acid esters,perfume oils and hair-care additives such as, for example, water-solublecationic polymers, protein derivatives, pantothenic acid andcholesterol.

A particularly suitable carrier is a gel containing 1 to 20% by weightof a soap, preferably ammonium oleate, or s an oil-in-water emulsioncontaining 1 to 25% by weight of a fatty component and 0.5 to 30% byweight of an emulsifier from the group consisting of anionic, nonionic,ampholytic or zwitterionic surfactants.

The oxidation dye precursors are incorporated in the carrier inquantities of 0.2 to 5% by weight and preferably in quantities of 1 to3% by weight, based on the dye as a whole. The content of2-nitroresorcinol in the hair dyes according to the invention may bebetween about 0.05 and 10 millimoles per 100 g of the hair dye.

Basically, the color can be oxidatively developed with atmosphericoxygen. However, it is preferred to use a chemical oxidizing agent,particularly when the hair is to be both colored and lightened.Particularly suitable oxidizing agents are hydrogen peroxide or adductsthereof with urea, melamine, or sodium borate and mixtures of suchhydrogen peroxide adducts with potassium peroxydisulfate.

A preparation of the oxidizing agent is preferably mixed with thepreparation of oxidation dye precursors and carrier immediately beforecoloring of the hair. The ready-to-use hair-coloring preparation formedshould preferably have a pH value of 6 to 10.

In a particularly preferred embodiment, the hair dyes are applied in amildly alkaline medium. The application temperatures may be in the rangefrom 15° C. to 40° C. After a contact time of about 30 minutes, the hairdye is removed from the hair to be colored by rinsing. The hair is thenwashed with a mild shampoo and dried. There is no need for washing witha shampoo in cases where a carrier of high surfactant content, forexample a coloring shampoo, has been used.

The following Examples are intended to illustrate the invention withoutlimiting it in any way.

EXAMPLES

Hair dyes according to the invention were prepared in the form of ahair-dyeing cream emulsion having the following composition:

    ______________________________________                                        C.sub.12-18 fatty alcohol                                                                             10     g                                              C.sub.12-14 fatty alcohol + 2EO sulfate,                                                              25     g                                              Na salt, 28%                                                                  Water                   60     g                                              Primary intermediate (component D1-D10)                                                               7.5    mmole                                          Color modifier (component M1, M2)                                                                     7.5    mmole                                          Na.sub.2 SO.sub.3 (inhibitor)                                                                         1.0    g                                              Concentrated ammonia solution                                                                         to pH 9.5                                             Water                   ad 100 g                                              ______________________________________                                    

The constituents were mixed together in this order. After addition ofthe oxidation dye precursors and the inhibitor, the emulsion was firstadjusted to pH 9.5 with concentrated ammonia solution and then made upwith water to 100 g.

The color was oxidatively developed with 3% hydrogen peroxide solutionas oxidizing agent. To this end, 50 g of hydrogen peroxide solution (3%)were added to and mixed with 100 g of the emulsion.

The dyeing cream was applied to about 5 cm long strands of standardized,90% grey, but not specially pretreated human hair and left thereon for30 minutes at 27° C. After dyeing, the hair was rinsed, washed with anormal shampoo and subsequently dried.

The following compounds were used as the primary intermediate components(components D1-D10):

D1: p-phenylenediamine

D2: p-tolylenediamine

D3: 2-chloro-p-phenylenediamine

D4: N-methyl-p-phenylenediamine

D5: N-(2-methoxyethyl)-p-phenylenediamine

D6: N,N-bis-(2-hydroxyethyl)-p-phenylenediamine

D7: p-aminophenol

D8: 2,5-diaminopyridine

D9: 1-phenyl-3-carboxyamido-4-amino-5-pyrazolone

D10: 2,4,5,6-tetraaminopyrimidine.

The following color modifiers were used:

M1: 2-nitroresorcinol

M2: 2-nitro-m-phenylenediamine.

The hair colors obtained are listed in the following Table:

    ______________________________________                                        Hair dye                                                                      example   Primary  intermediate  Modifier Tint                                ______________________________________                                        1         D1       M1            Dark brown                                   2         D2       M1            Brown                                        3         D3       M1            Dark brown                                   4         D4       M1            Dark violet                                  5         D5       M1            Dark violet                                  6         D6       M1            Dark violet                                  7         D7       M1            medium brown                                 8         D8       M1            Deer-brown                                   9         D9       M1            Grey-magenta                                 10         D10     M1            Yellow-brown                                 11        D2       M2            Brown-violet                                 12         D10     M2            Red-brown                                    ______________________________________                                    

We claim:
 1. A process for the production of oxidation dyes, wherein theimprovement comprises the use of 2-nitroresorcinol, its salts, ormixtures thereof as a color modifier together with known primaryintermediate components selected from the group consisting of primaryaromatic amines, diaminopyridines, heterocyclic hydrazone derivatives,aminopyrazolone derivatives and tetraaminopyrimidines, wherein saidcolor modifier and primary intermediate components are present inquantities of 0.2 to 5% by weight of the total composition.
 2. Hair dyescontaining a color modifier and one or more primary intermediatecomponents selected from the group consisting of primary aromaticamines, diaminopyridines, heterocyclic hydrazone derivatives,aminopyrazolone derivatives and tetraaminopyrimidines, wherein saidcolor modifier and primary intermediate components are present inquantities of 0.2 to 5% by weight of the total composition in a carrier,wherein the improvement comprises the presence of 2-nitroresorcinol as acolor modifier.
 3. Hair dyes as claimed in claim 2, primary intermediateand color modifier in a molar ratio of 1:0.5 to 1:2, and2-nitroresorcinol in a quantity of 0.05 to 10 millimoles per 100 g ofthe hair dye.
 4. Hair dyes as claimed in claim 3, wherein the carrier isa gel containing 1 to 20% by weight of a soap or an oil-in-wateremulsion containing 1 to 25% by weight of a fatty component and 0.5 to30 % by weight of an emulsifier selected from the group consisting ofanionic, nonionic, ampholytic, or zwitterionic surfactants.
 5. Hair dyesas claimed in claim 2, wherein the carrier is a gel containing 1 to 20%by weight of a soap or an oil-in-water emulsion containing 1 to 25% byweight of a fatty component and 0.5 to 30% by weight of an emulsifierselected from the group consisting of anionic, nonionic, ampholytic, orzwitterionic surfactants.